Is our suspension setup correctly by aftermarket strut MFR's? Is the bias correct?

As I get closer and closer to completing my racecar and reasearch more and more I'm tripping over things that keep raising questions. The most recent is our chassis cornerweights in comparison with Evo VII-IX series. The EVO VII-IX etc chassi and the 3/S are corner weighed very similar in race form. They both carry weight similarly, have nearly identical roll centers, centers of gravity, brake bias, aero, and etc.

To wrap this all together, Evo struts and 3/S TT aftermarket struts are retailed by several MFR's already setup with a spring rate of 10K front / 8K rear... 12K front / 10K rear, and etc. What I've found in the Evo community is the guys doing their homework regarding suspensions such as Meullerized, GT Works, Moton, JRZ, and AST Engineering have engineered and improved suspensions on the EVO chassi and determined if the front is sprung more, "you're doing it wrong". What that community is seeing is suspensions engineered and retailed nearly reverse. 10K front's / 12K rears, or 12K fronts and 14K rears.

If that's the case do any 3S suspensions out there have the spring and valving right (if the rear is suppose to have more spring than the front)?

So what is the reasoning and the debacle? Well, Supercar Engineering Evo Suspension Conversion adapters afford us the ability to bolt on Evo suspensions. Often the spring and valving is based off the weight bias of the vehicle. The weight and suspension bias on both is nearly identical. You would think if that were the case they would be very close to one another regarding setup?


Here's the corner weights of a 3/S (obviously it's not balanced properly and I'm not going to say whose car this is but you can see the bias)
http://i788.photobucket.com/albums/y...psb41a5acd.jpg


Corner weights of track Evo
http://i788.photobucket.com/albums/y...ps3931e394.jpg

Now here's what's available: *Note these are not Tooner shocks

Evolution IV-IX Coilovers/Springs
Welcome to Muellerized Suspension Systems

For pricepoints ranging anywhere from $3500 - $15,000 (take your breath away expensive) you get the read deals with spring rates and valving quite the opposite of what we're used to seeing. Like 14K in the rear and 11K in the front. So what gives? Are Z16A chassis supposed to be setup for more front spring or what?

A very typical OEM bias on an EVO VII-IX (which has the same suspension that we can adapt to with Supercar Adapters) is distributed 1000 lbs in the front corners and 650 lbs in the rear corners. The ideal spring rates for those weights typically for Ohlin DFV Road and Track, JRZ's, Moton and AST 5000's is 10k front and 12K rear...

Are the motion ratios even remotely close? What about ride frequency? There's a LOT of calculations & testing to do...

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Originally Posted by DocWalt

Are the motion ratios even remotely close? What about ride frequency? There's a LOT of calculations & testing to do...

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If you buy a set of Meullerized DFV's for a 3000gt (which they make now BTW) that's how John Meuller reccomends they come. More spring in the rear. However, you can custom order them however you want. ;)

Tooner shocks are doing it wrong.

Forgot link... Welcome to Muellerized Suspension Systems

I know they make them, Nate's planning on buying a set.

I wouldn't be at all surprised if the "tooner" companies got it wrong, FWIW.

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Originally Posted by J. Fast

Here's the corner weights of a 3/S (obviously it's not balanced properly and I'm not going to say whose car this is but you can see the bias)
[COLOR=#000000][FONT=Calibri][SIZE=3]http://i788.photobucket.com/albums/y...psb41a5acd.jpg

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Bent frame? lol

Unfortunately I can’t add much to this subject right now but I'm very interested in the info.

J what about the spring ratings on ECS struts, you thinking that the spring rates are backwards?

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Originally Posted by green-lantern

Bent frame? lol

Unfortunately I can’t add much to this subject right now but I'm very interested in the info.

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No man, this was on a racetrack. The suspension is not properly balanced. Not even remotely close. Look at the diagonals.

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Originally Posted by 2fnloud

J what about the spring ratings on ECS struts, you thinking that the spring rates are backwards?

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I don't think so. From most of my research what I've found is Evo's come stock with a similar front to rear spring bias (front higher sprung) as compared to the 3/S. But they've been significantly improved with an inverted spring bias (rear heavy sprung) and different valving.

EDIT: Many lower market Evo suspension retailers still sell shocks with high front and low rear spring rates. The pro's who own suspension tuning facility's will laugh at you when you discuss what you have on there. If the fronts are higher than the rears they know right out of the gate your suspension isn't setup correctly.

Well valving will not change, I am not willing to leave the ECS strut.

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Originally Posted by 2fnloud

Well valving will not change, I am not willing to leave the ECS strut.

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This friggin sucks man... Nowhere to get answers for stuff like this on our platform. No legitimate suspension shops that just just deal with suspension and have shock dynos. I'm totally in the dark :(

I would be totally willing to loan out my new in box struts if we had a dyno available

I'm sure Nascar shops are a dime a dozen in the Northeast. Anything close to you? I've been working with AMS trying to figure out what's going to work best for me if I want to go down the JRZ rabbit hole. It's looking like 14k rear and 11K fronts. If I throw a huge splitter on possibly 14K/14K (front/rear)?

nothing with in a 2 hour drive of my city

Are you trying to promote oversteer, neutralise understeer with the stiffer rear springs?.

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Originally Posted by KeithMac

Are you trying to promote oversteer, neutralise understeer with the stiffer rear springs?.

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No, I'm trying to set the spring rate.

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Originally Posted by Andrew @ GTWorx

....Unlike the front strut which is pretty much mounted at the hub, a 5k spring rate in the rear does not mean a 5k rate at the wheelhttp://images.intellitxt.com/ast/adTypes/icon1.png. Essentially the suspension arm is a moment arm....placing the spring inwards towards the pivot point means it needs to be stiffer. Sometimes you'll see people mention the "motion ratio." For the front EVO with the strut based suspension, it's close to 1 (almost). For the rear, it's somewhere between .6 to .9.

To get the "wheel" rate, you multiply the spring rate by the square of the motion ratio.

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What he said here is... When the pickup point for the bottom of a rear strut is inboard from the rear hub assembly there's a pivot/moment arm which reduces the actual sprung weight at the wheel. You have to multiply the spring rate by the moment calculation in order to realize the actual rate. I would suspect that number is somewhere between .7 and .8 on a 3/S with Supercar Suspension Adapters. So a 12K rear spring actually behaves like a 9K in the rear once the moment reduction is realized.

In english... If you want 600lbs of spring at the rear tire you need like 800lbs of spring on the rear strut.

Contined... Since the front strut is inline with the hub and not offset... and the ratio is 1 to 1 then if you want 600lbs of spring at the wheel then you need 600lbs of spring. I believe that's the correct interpretation? Is that how that read guys?

That is how I would pick it up, but doesn't that same truth apply to the rear?

That's how I understood what you posted...

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Originally Posted by 2fnloud

That is how I would pick it up, but doesn't that same truth apply to the rear?

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No, it doesn't apply to the rear because the rear strut doesn't terminate at the hub. It's offset. The offset difference is a lever arm.

Think of it like a teeter todder. Say there's a 600lb weight on one end and a 300lb weight on the other. You can balance out both by moving the fulcrum. In an illustrative way the reduction is the distance moved from body center.

OK I thought it was really close to hub, my bad
'

As I've posted before, there's a shop 15 minutes from my house with a shock dyno. We need fittings made before I'm even going to call them, I'm not wasting my time nor looking like a fool when I can't come through.

I know, who can make the fitting? Jeremy could you make the fitting?

Depending on how your top hats are set....front motion ratio is .93 to .98. Rear is like 1.2. I haven't finished measuring the rear yet. On rear your spring will be less than front on 3s for 99% of people.

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Originally Posted by anyonebutme

Depending on how your top hats are set....front motion ratio is .93 to .98. Rear is like 1.2. I haven't finished measuring the rear yet. On rear your spring will be less than front on 3s for 99% of people.

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Will this change depending on wether or not we utilize camber plates? Where are you and Andrew @ GT Worx deriving that rear differential number from?

I'm getting conflicting info regarding setting this up and it's really frustrating.

How is the rear motion ratio greater than 1?

What I've coming my way... JRZ Triple Adjustable. I bought them from a guy on Evo M.

http://img252.imageshack.us/img252/8610/dsc0030tz.jpg

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Originally Posted by 2fnloud

I know, who can make the fitting? Jeremy could you make the fitting?

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Make adapters for the shock dyno? I'm guessing this requires upper and lower front and rear adapters? I suppose I could make A-frames. What size hole at the top and bottom for mounting, 1/2"?

I'm not free this coming up weekend but next weekend. I can make something.

1/2" should work. Need to keep some method of allowing the wires for ECS to be connected. duke_3k (IIRC that's his username) offered an ECS controller to put the shocks into the correct valving positions.

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Originally Posted by green-lantern

Bent frame? lol

Unfortunately I can’t add much to this subject right now but I'm very interested in the info.

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Hahahaha, well, maybe... It's from my car. Taken a few second from this pic...

http://imageshack.us/a/img841/3540/blue1w.jpg

This is from a friend (Ray's camera Jer)..
http://imageshack.us/a/img864/6268/img3947v.jpg

Lifting the rear inside tire is very common. This really isn't even the best pic. I have one at home that was during hard braking and transitioning into turn in where the rear is a good 5" off the ground. This is with the 14/10 front/rear setup. (787lbs/ 564lbs)

That's not anywhere near enough. That's why I recently switched to 1300 up front and 1100 in the rear. We'll see how that works this year because I was giving away a bit by lifting the tire that much. I had Hal machine me up some adapters to fit a proper 2.5" Hypercoil.
http://imageshack.us/a/img705/2864/coild.jpg


To be perfectly honest, I wanted a higher rate than even the 1300's. A few of the faster guys are in the 2000's for spring rates on a similarly weighted car.

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Originally Posted by DocWalt

How is the rear motion ratio greater than 1?

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Spring is behind the hub while the pivot is in front of the hub....so spring travels a longer distance then the hub. The evo mounts the spring to the control arm iirc, meaning its possible it has a Mr less than 1.

You can have JIC FLT TAR's Muellerized, E. He revalves them and puts a pretty hefty spring package on them. 14K in the rear and 11K in the fronts. I don't know where he's deriving his setup for Evo's and 3/S but the bias he AST, AMS, GT Worx, and JRZ are coming up with is way different. They're saying more spring in the rear if not equal to the rate of the front?

I'm trying to separate the music from the noise.

Wait, what? You think you're frame is bent Erron? Is that from the divider hop at 80, from the cage, something else, or are you just being silly?

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Originally Posted by anyonebutme

Spring is behind the hub while the pivot is in front of the hub....so spring travels a longer distance then the hub. The evo mounts the spring to the control arm iirc, meaning its possible it has a Mr less than 1.

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Pivot is that far out? It's been a long time since I've looked at the rear suspension in that much detail.

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Originally Posted by Erron Spalsbury

A few of the faster guys are in the 2000's for spring rates on a similarly weighted car.

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Just thinking for a moment, 20K seems like a whole lot of spring for a 3000lb car. That's 1100lbs of rebound per spring on a corner. I bet it unloads aircraft style unless you have double that in aero to keep it planted. Doesn't sound achievable without a tubular or superbody chassi? What kinds of 3000lb cars are we discussing here? Unlimited's :p?

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Originally Posted by DocWalt

Pivot is that far out? It's been a long time since I've looked at the rear suspension in that much detail.

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Trailing arm suspension. It might be as low as 1.12....but its definitely >1.

Quote:

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Originally Posted by anyonebutme

Spring is behind the hub while the pivot is in front of the hub....so spring travels a longer distance then the hub. The evo mounts the spring to the control arm iirc, meaning its possible it has a Mr less than 1.

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Isn't one of the major factors considered in calculating the motion ratio based off the inclination angle of the strut?

From what I'm reading from WORKS the motion ratio shouldn't be greater than 1:1 in the rear unless the top anchor and bottom anchor suspension mounts cast a projection line which falls inside of the tire patch. I don't think our cars do that. I think we have something like 12% on the projection angle and an additional 5-10% on the inclination angle which puts us in the .78:1 range in the rear?

I wish I knew wtf was right vs wrong so I could check my sanity and my wallet. How are you arriving at your numbers bro?

https://docs.google.com/viewer?a=v&q...kUCy9S9wqNxcnw

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Originally Posted by J. Fast

Just thinking for a moment, 20K seems like a whole lot of spring for a 3000lb car. That's 1100lbs of rebound per spring on a corner. I bet it unloads aircraft style unless you have double that in aero to keep it planted. Doesn't sound achievable without a tubular or superbody chassi? What kinds of 3000lb cars are we discussing here? Unlimited's :p?

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Hahaha, I was just being silly about the bent frame comment.

A number of the Vipers are in the 2000lb spring range. I think if you ask around you'd find a lot of the faster cars are way up there in spring rate.

I had my buddy (the other Jake) take a ride with me and help setup the suspension. This is the driver I just posted over the weekend that took 5th in F1000 down at COTA that I sponsor. A super great guy that you have to hang with. I raced with him for a few years through the SCCA. In a brief nutshell you just want the suspension to not bounce on rebound. A nice compression with a swift rebound without any oscillation or hop. (higher dampening rate will slow this) I'm honestly a little worried about how long the JIC's will be able to take this amount of spring since it's darn near twice what they had in mind when they made them. I'm two clicks from maximum on the front, rears are one click of the bottom, but I don't want max. I want it to be able to absorb at a fast rate but not not be so stiff that it doesn't have time to absorb. Basically, the lowest setting possible without any bounce.

Some say..."you can never have enough spring". But I think that was from a kart driver. :P

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Originally Posted by J. Fast

Isn't one of the major factors considered in calculating the motion ratio based off the inclination angle of the strut?

From what I'm reading from WORKS the motion ratio shouldn't be greater than 1:1 in the rear unless the top anchor and bottom anchor suspension mounts cast a projection line which falls inside of the tire patch. I don't think our cars do that. I think we have something like 12% on the projection angle and an additional 5-10% on the inclination angle which puts us in the .78:1 range in the rear?

I wish I knew wtf was right vs wrong so I could check my sanity and my wallet. How are you arriving at your numbers bro?

https://docs.google.com/viewer?a=v&q...kUCy9S9wqNxcnw

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I'll expand when I get home....we don't have struts in the rear. Look at it from the side not the rear.

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Originally Posted by anyonebutme

Trailing arm suspension. It might be as low as 1.12....but its definitely >1.

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Quote:

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Originally Posted by anyonebutme

I'll expand when I get home....we don't have struts in the rear. Look at it from the side not the rear.

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Gotcha, please elaborate! This would be good to know!

Setting up suspension needs to be sticky type stuff!

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Originally Posted by Erron Spalsbury

Hahaha, I was just being silly about the bent frame comment.

A number of the Vipers are in the 2000lb spring range. I think if you ask around you'd find a lot of the faster cars are way up there in spring rate.

I had my buddy (the other Jake) take a ride with me and help setup the suspension. This is the driver I just posted over the weekend that took 5th in F1000 down at COTA that I sponsor. A super great guy that you have to hang with. I raced with him for a few years through the SCCA. In a brief nutshell you just want the suspension to not bounce on rebound. A nice compression with a swift rebound without any oscillation or hop. (higher dampening rate will slow this) I'm honestly a little worried about how long the JIC's will be able to take this amount of spring since it's darn near twice what they had in mind when they made them. I'm two clicks from maximum on the front, rears are one click of the bottom, but I don't want max. I want it to be able to absorb at a fast rate but not not be so stiff that it doesn't have time to absorb. Basically, the lowest setting possible without any bounce.

Some say..."you can never have enough spring". But I think that was from a kart driver. :P

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Lemkuhl... Formula guy? We've met. I've seen his new toy on FB and seen him comment on Racing Tech Tip's every once in a blue moon.

I can't answer this stuff E, only comment on what's out there. It's a little outside of my knowlege ATM. I'm learning quickly tho. I will have my mind and hands wrapped around it real soon (I might even visit Claude Rouelle and see if he can squeeze me in since he's across the way).

From what I'm hearing and reasearching so far regarding spring rates it's the other way around. We want the least amount of spring that which promotes the best tire contact in all situations. If we were on a flat track at max speed like in Nascar then big spring, yes. Autocross, where you can jack a suspension and go two wheeling, yes. Since were in compression and rebound and pitch and roll and speed and comfort is more about tires staying planted, then we want les spring and better shock valving.

It sounds like it's very difficult to keep a chassi settled with a huge spring. From most of what I can find the highest spring rate for an Evo which is quite comparable to ours is a 700lb spring. That's on a world championsip vehicle or something like what Dave K drives.

No, that's THE Jake, this is the OTHER Jake.
Jake Latham - Yep.

Allow me to toss out a few thoughts and a comment.
How hard is it to keep a kart chassis settled? (ie. no springs) I realize these are worlds apart but there's some knowledge there than can transfer over. For instance, how do you hold the most grip in a kart? By allowing your body to transfer to the outside of the seat or weight transfer in general. The top kart guys will you tell you they literally lean OUT in a corner and even do so before the corner to have the weight where it needs to be during the initial "bite" or turn in. So transferring weight needs to be quick and concise. If you're waiting to bound up a spring and for the car to physically lean out you've lost time. (see what I'm trying to convey?) This is a fun one to do in a parking lot. Give the wheel a solid, quick crank in one direction or the other at say 30mph and you'll see the delay I'm referring to.

The big key here isn't what "should" work best, it's what does, for how you drive your car. I lift that inside tire on every corner, left or right. Think about the trophy photo in my office you've seen. The left rear is way off the ground. I'm giving up traction for sure. Now if I hadn't braked as late or snapped into the corner as hard I probably could have carried more speed. In the heat of the moment though, I drive. I obviously have something to gain by going to a higher spring rate. Not all will, but a lot do. :) This is why I went with an easily swap-able spring like the Hyperco's. I have a ton to choose from for not a lot of money. If it doesn't work the way I want it to, a couple hundo later and it's a whole 'nuther car.

The 1100's I have for the rear are 2.5" but they are actually Eibachs that came off of Philip's at SCE car. He said it made the car feel "twitchy". I LOVE the twitch. Small inputs make the car turn and turn like, "Holy crap, I was only thinking about turning and now I'm turning!" kind of thing. Har-har-har-hootenanny-gigity!

Awesome stuff. Here to suck up the knowledge.